Advances in technology, particularly advances in growth techniques such as molecular beam epitaxy, have made it possible to tailor-make crystalline multilayer structures. Such structures, described as heterostructures, have made possible a host of promising electronic and optoelectronic devices. Many of the electronic devices have been aimed at providing electronic switches with faster switching speeds and to this surface have sought to utilize the increased mobility of the charge carriers, holes and electrons, attainable in multilayer structures, such as superlattices.
However, one problem that has persisted in many such devices is that the transit time for the active charge carriers to travel the relatively long distance between an input node (source) and an output node (drain) has restricted the speed with which the device can be switched between its "on", or low impedance state, and its "off", or high impedance state. A related problem that has characterized other such devices is that the switching speed has been limited by relatively long recombination times, the time it takes free electrons and holes to recombine, and so to reduce the number of charge carriers available for conduction.
An object of the present invention is a device in which these effects that limit switching speeds are reduced so that shorter switching times can be attained.